Access method and apparatus

ABSTRACT

Embodiments of the present invention provide an access method, including: sending, to an access point, a first frame that carries uplink transmission requirement information; and if a second frame that carries information about an uplink transmission resource is received from the access point within agreed time period, sending uplink multi-user transmission data to the access point, where the uplink multi-user transmission data is transmitted on the uplink transmission resource; or if the second frame is not received within an agreed time period, accessing, by a station, a channel in a contention access manner that is based on carrier sense CSMA/CA. According to the method provided in the embodiments of the present invention, a channel access manner can be managed, a congestion degree of a system can be decreased, and channel utilization can be increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/105514, filed on Nov. 11, 2016, which claims priority toChinese Patent Application No. 201510993268.4, filed on Dec. 25, 2015,The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to the field of wireless communicationstechnologies, and in particular, to an access method and apparatus.

BACKGROUND

To resolve a WLAN quality of service (Quality of Service, QoS) problem,the Institute of Electrical and Electronics Engineers (Institute ofElectrical and Electronics Engineers, IEEE) introduces the IEEE802.11estandard.

The IEEE802.11e extends a distributed coordination function (DistributedCoordination Function, DCF) channel access mechanism at a Media AccessControl (Medium Access Control, MAC) layer of the original IEEE802.11,to form enhanced distributed channel access (Enhanced DistributedChannel Access, EDCA). The EDCA enhances the DCF mechanism,distinguishes between priorities of different service applications,guarantees a channel access capability of a high-priority service, andguarantees bandwidth of the high-priority service to some extent.

In the 802.11e protocol, there are four AC (Access Category, accesscategory) queues, including AC_BK (Background traffic), AC_BE (BestEffort traffic), AC_VI (Video traffic), and AC_VO (Voice Traffic), anddifferent EDCA parameters may be configured, so that a high-priority ACqueue has more sending opportunities and less waiting time. In theprotocol, an ACI (Access Category Index, access category index) is usedto identify the foregoing access category. A queue is selected accordingto a priority carried in a data frame, so as to ensure QoS in a wirelesslocal area network environment.

An access point (Access Point, AP) may add information about an EDCAparameter set to a beacon frame (Beacon Frame), a probe (Probe) responseframe, an association response frame, or a re-association responseframe, and the parameter set indicates parameters of EDCA channel accessmanners of different access categories (Access Catagory), including anAIFSN, ACM, an ACI, an ECWmin, an ECWmax, and a TXOP Limit.

A larger value of the AIFSN (Arbitration Inter Frame Spacing Number,arbitration interframe spacing number) indicates longer idle waitingtime of a user.

The ECWmin (Exponent form of CWmin, Exponent form of Cwmin) and theECWmax (Exponent form of CWmax, Exponent form of Cwmax) determine anaverage backoff time value, and larger values of the two parametersindicate a longer average backoff time of the user.

The TXOP Limit (Transmission Opportunity Limit, transmission opportunitylimit) indicates maximum duration for occupying a channel aftercontention of the user succeeds once. A larger value of the TXOP Limitindicates longer duration for occupying a channel by the user once. Ifthe value is 0, only one packet can be sent each time after a channel isoccupied, and a channel needs to be contended for again for sending apacket again.

The ACM (Admission Control Mandatory, admission control mandatory)indicates whether an access category needs admission control. If a bitis 0, a corresponding access category does not need admission control.If the bit is 1, admission control needs to be used before an accessparameter of the access category is used for transmission.

In a current application, four EDCA parameter sets are configured bydefault to separately correspond to different queues, and each parameterset takes effect on an entire BSS (Basic Service Set, basic serviceset). That is, in the BSS, QoS characteristics of all STAs areconsistent, and if two STAs transmit data of a same queue, the STAs usea same EDCA parameter.

In an existing application, a STA can perform random access based on atime domain only on a main channel, and therefore random accessefficiency is relatively low. In uplink multi-user transmission,multiple stations can perform parallel random access on multiplechannels at the same time, to improve the random access efficiency.However, in this access manner, multi-user transmission needs to beorganized after an AP successfully obtains a channel by means ofcontention, and a probability that an AP successfully obtains a channelby means of contention needs to be increased.

SUMMARY

Embodiments of the present invention provide an access method andapparatus, so as to enable, as far as possible, multiple stations toperform parallel random access on multiple channels at the same time,and improve random access efficiency. To achieve the foregoingobjective, the following technical solutions are used in the embodimentsof the present invention.

According to a first aspect, an embodiment of the present inventionprovides an access method, including:

sending, to an access point, a first frame that carries uplinktransmission requirement information; and

if a second frame that carries information about an uplink transmissionresource is received from the access point within an agreed time period,sending uplink multi-user transmission data to the access point, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource; or if the second frame is not received within anagreed time period, accessing, by a station, a channel in a contentionaccess manner that is based on carrier sense CSMA/CA.

With reference to the first aspect, in a first implementation of thefirst aspect, the access method further includes: receiving a radioframe sent by the access point, where the radio frame indicates sendingtime (or may be referred to as target sending time, that is, a presetsending time point of the second frame) of the second frame, and theradio frame is an association response frame, a beacon frame, or aresponse frame of the access point to a received data frame. Further,the agreed time period may be obtained according to the sending timepoint of the second frame.

According to a second aspect, an embodiment of the present inventionprovides an access method, including:

receiving a radio frame sent by an access point, where the radio frameindicates an access manner for performing channel access, and the radioframe is an association response frame, a beacon frame, or a responseframe of the access point to a received data frame; and

if a second frame that carries information about an uplink transmissionresource is received from the access point within an agreed time period,sending uplink multi-user transmission data to the access point, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource; or if the second frame is not received within anagreed time period, accessing, by a station, a channel in aCSMA/CA-based contention access manner.

With reference to the second aspect, in a first implementation of thesecond aspect, the access manner includes at least one of the following:the contention access manner that is based on carrier sense multipleaccess with collision avoidance CSMA/CA, a contention access manner thatis based on orthogonal frequency division multiple access OFDMA, or anOFDMA-based scheduling access manner.

With reference to the second aspect or the first implementation of thesecond aspect, in a second implementation of the second aspect, thesecond frame or the radio frame further includes indication informationthat indicates the following or the following is agreed in advance in aprotocol:

when the data frame carries a buffer status report BSR or the data framedoes not include an unfragmented data frame, the data frame is sent inthe OFDMA contention access manner.

According to a third aspect, an embodiment of the present inventionprovides an access method, including:

receiving, from an access point, a first frame that carries informationabout an uplink transmission resource;

sending, to the access point, a second frame that carries uplinktransmission requirement information, and disabling a CSMA/CA-basedcontention access manner or disabling a backoff timer; and

if a third frame that carries information about an uplink transmissionresource is received from the access point within an agreed time period,sending uplink multi-user transmission data to the access point, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource; or if the third frame is not received within anagreed time period, accessing, by a station, a channel by enabling theCSMA/CA-based contention access manner.

When there are many connected stations, a large quantity of stations mayparticipate in CSMA/CA contention and OFDMA contention. Consequently, aprobability of a collision between stations is greatly increased, andchannel utilization is decreased. Therefore, according to the accessmethod provided in this embodiment of the present invention, a channelaccess manner can be managed, a congestion degree of a system can bedecreased, and the channel utilization can be increased.

Optionally, in this embodiment of the present invention, the agreed timeperiod may be counted by using a timer, where an initial value of thetimer is specified by the access point or is agreed in a protocol.Further, when a channel on which the uplink transmission resource islocated is idle, a value of the timer progressively decreases with time;or when the channel is busy, progressive decreasing of a value of thetimer is suspended. Still further, the value of the timer is updatedwhen the channel is busy or a trigger frame that carries informationabout an uplink transmission resource is received or a trigger frame forrandom access is received or a trigger frame that carries a trainingsequence is received, and a manner of updating the value of the timer isadding a constant to or multiplying a constant by a current value of thetimer.

Optionally, the uplink transmission requirement information includes atleast one of the following: a packet arrival interval, packet sizeinformation, or traffic rate information.

Corresponding to the method provided above, the embodiments of thepresent invention further provide a corresponding method on an accesspoint side.

According to a fourth aspect, an embodiment of the present inventionprovides an access method, including: receiving, from a station, a firstframe that carries uplink transmission requirement information;

sending, to the station, a second frame that carries information aboutan uplink transmission resource; and

receiving uplink multi-user transmission data from the station, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource.

According to a fifth aspect, an embodiment of the present inventionprovides an access method, including:

sending a radio frame to a station, wherein the radio frame indicates anaccess manner (for example, whether to use an OFDMA-based access manneror whether to disable a CSMA/CA-based contention access manner) forperforming channel access, and the radio frame is an associationresponse frame, a beacon frame, or a response frame of the access pointto a received data frame;

sending, to the station, a second frame that carries information aboutan uplink transmission resource; and

receiving uplink multi-user transmission data from the station, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource.

In the fifth aspect, the access point may indicate, according toscenario information by using the radio frame, the access manner forperforming channel access. For example, in an intensive deployment(coverage areas of many stations or access points are heavilyoverlapped) scenario, an access point may instruct a station to disablethe CSMA/CA-based contention access manner. The access point mayinstruct the station to use the OFDMA-based access manner. A contentioncollision between stations can be reduced, and a throughput rate of anentire system can be improved. Otherwise, in a scenario with fewstations, an access point may instruct a station to enable theCSMA/CA-based contention access manner. The access point controls theaccess manner of the station, and system resources can be effectivelyused.

According to a sixth aspect, an embodiment of the present inventionprovides an access method, including:

sending, to a station, a first frame that carries information about anuplink transmission resource;

receiving, from the station, a second frame that carries uplinktransmission requirement information;

sending, to the station, a third frame (such as a trigger frame) thatcarries information about an uplink transmission resource; and

receiving uplink multi-user transmission data from the station, wherethe uplink multi-user transmission data is transmitted on the uplinktransmission resource.

It should be noted that in the sixth aspect, the information about theuplink transmission resource in the third frame may further include anidentifier of one or more stations that use the uplink transmissionresource.

Corresponding to the method provided above, the embodiments of thepresent invention further provide a corresponding apparatus.

According to a seventh aspect, an embodiment of the present inventionprovides an access apparatus, including:

a sending module, configured to send, to an access point, a first framethat carries uplink transmission requirement information; and

a processing module, configured to: if a second frame that carriesinformation about an uplink transmission resource is received from theaccess point within an agreed time period, send uplink multi-usertransmission data to the access point, where the uplink multi-usertransmission data is transmitted on the uplink transmission resource; orif the second frame is not received within an agreed time period,access, by a station, a channel in a contention access manner that isbased on carrier sense CSMA/CA.

According to an eighth aspect, an embodiment of the present inventionprovides an access apparatus, including:

a receiving module, configured to receive, from a station, a first framethat carries uplink transmission requirement information; and

a sending module, configured to send, to the station, a second framethat carries information about an uplink transmission resource, where

the receiving module is further configured to receive uplink multi-usertransmission data from the station, where the uplink multi-usertransmission data is transmitted on the uplink transmission resource.

The sending module is further configured to send the second frame to oneor more stations, where the second frame indicates the one or morestations to perform uplink multi-user transmission, and the one or morestations include the station that sends the first frame.

The following provides some apparatuses corresponding to the methods byusing only a station side as an example. The apparatus on the accesspoint side may be provided in a similar manner, and details are notdescribed herein.

According to a ninth aspect, an embodiment of the present inventionprovides an access apparatus, including:

a receiving module, configured to receive a radio frame sent by anaccess point, where the radio frame indicates an access manner forperforming channel access, and the radio frame is an associationresponse frame, a beacon frame, or a response frame of the access pointto a received data frame; and

a processing module, configured to: if a second frame that carriesinformation about an uplink transmission resource is received from theaccess point within an agreed time period, send uplink multi-usertransmission data to the access point, where the uplink multi-usertransmission data is transmitted on the uplink transmission resource; orif the second frame is not received within an agreed time period,access, by a station, a channel in a CSMA/CA-based contention accessmanner.

According to a tenth aspect, an embodiment of the present inventionprovides an access apparatus, including:

a receiving module, configured to receive, from an access point, a firstframe that carries information about an uplink transmission resource;

a sending module, configured to send, to the access point, a secondframe that carries uplink transmission requirement information; and

a processing module, configured to: disable a CSMA/CA-based contentionaccess manner or disable a backoff timer; and if a third frame thatcarries information about an uplink transmission resource is receivedfrom the access point within an agreed time period, send uplinkmulti-user transmission data to the access point, where the uplinkmulti-user transmission data is transmitted on the uplink transmissionresource; or if the third frame is not received within an agreed timeperiod, access, by a station, a channel by enabling the CSMA/CA-basedcontention access manner.

Some technical features in the foregoing apparatus embodiments, such asthe timer, the uplink transmission resource, the trigger frame, and theradio frame, are similar or corresponding to some technical features inthe foregoing method embodiments, and no repeated descriptions are givenherein.

According to the embodiments of the present invention, multiple stationsare enabled, as far as possible, to perform parallel random access onmultiple channels at the same time, and random access efficiency isimproved. There are two manners for increasing an opportunity that theaccess point obtains a channel. One is that the station delayscontention or decreases intensity of contending for a channel by thestation, and the other is that after obtaining a channel by means ofcontention, the station hands over a control right to the access point,and the access point sends a multi-user transmission trigger frame.

BRIEF DESCRIPTION OF DRAWINGS

Accompanying drawings are included and constitute a part of thespecification, and a same number describes a same component. Theaccompanying drawings describe embodiments of the present invention andare intended to, together with the described content, explain principlesof the present invention.

FIG. 1 is a schematic flowchart of a frame exchange of STA randomaccess;

FIG. 2 is a schematic diagram of a basic structure of an uplink randomaccess packet;

FIG. 3A is a schematic flowchart of a frame exchange in a scenario 1according to an embodiment of the present invention;

FIG. 3B is a schematic flowchart of another frame exchange in a scenario1 according to an embodiment of the present invention;

FIG. 3C is a schematic flowchart of a frame exchange in a scenario 2according to an embodiment of the present invention;

FIG. 3D is a schematic flowchart of a frame exchange in a scenario 3according to an embodiment of the present invention;

FIG. 3E is a schematic flowchart of a frame exchange in a scenario 4according to an embodiment of the present invention;

FIG. 3F is a schematic flowchart of a frame exchange in a scenario 5according to an embodiment of the present invention;

FIG. 3G-1 and FIG. 3G-2 are schematic diagrams in which multipletransmission manners jointly work;

FIG. 4 is a schematic flowchart of a frame exchange of an access methodaccording to Embodiment 4 of the present invention;

FIG. 5 is a schematic diagram of several situations in which a timerneeds to be used;

FIG. 5A is a schematic working diagram of a first timer according to anembodiment of the present invention;

FIG. 5B is a schematic working diagram of a second timer according to anembodiment of the present invention;

FIG. 5C is a schematic working diagram of a third timer according to anembodiment of the present invention;

FIG. 5D is a schematic working diagram of a fourth timer according to anembodiment of the present invention;

FIG. 6A is a first schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention;

FIG. 6B is a second schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention;

FIG. 6C is a third schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention;

FIG. 6D is a fourth schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention;

FIG. 7 is a schematic flowchart of a frame exchange of a transmissionmode conversion method according to an embodiment; and

FIG. 8 shows an access apparatus according to an embodiment of thepresent invention.

DESCRIPTION OF EMBODIMENTS

Various embodiments of the present invention are referenced in detail,and an example is shown in the accompanying drawings. Althoughdescriptions are provided with reference to these embodiments, it may beunderstood that these embodiments are not used to limit the presentinvention to these embodiments. Instead, the present invention isintended to cover a replacement technology, modification, and anequivalent technology that may be included within the spirit and scopeof the present invention limited in the appended claims. In addition, inthe following detailed descriptions of the present invention, manyspecific details are described to provide a thorough understanding ofthe present invention. However, it may be understood that in an actualapplication, these specific details of the present invention may not beincluded. A well-known method, process, component, and circuit are notdescribed in detail in another example, so as to prevent various aspectsof the present invention from being unnecessarily blurred.

In an IEEE 802.11ax system, a station (English: station, STA for short)performs uplink access mainly in the following several manners:

Manner 1: a contention access manner that is based on carrier sensemultiple access with collision avoidance (English: Carrier SenseMultiple Access with Collision Avoidance, CSMA/CA for short).

Manner 2: a contention access manner that is based on orthogonalfrequency division multiple access (English: Orthogonal FrequencyDivision Multiple Access, OFDMA for short).

Manner 3: an OFDMA-based scheduling access manner.

In the foregoing manner 1, a STA may spontaneously perform access bymeans of carrier sense when a channel is idle. In the foregoing manner2, after receiving a trigger frame for random access (English: triggerframe for random access, TFR for short) sent by an AP, a STA mayrandomly select a resource block to perform access. In the foregoingmanner 3, after receiving a trigger frame (English: trigger frame) sentby an AP, a STA may perform data transmission on a corresponding channelaccording to an indication of the trigger frame. To enable an AP to senda trigger frame to a STA, the STA needs to send a buffer size report(English: Buffer Size Report, BSR for short) to the AP, and the BSR maybe sent in the foregoing manner 1, manner 2, or another manner.

The OFDMA-based scheduling access manner may further be implemented byusing another access method. For example, a STA may send a radio frameto an AP in the manner 1 or the manner 2, and the radio frame carriesindication information that is used to indicate that the AP may send atrigger frame to trigger the STA to send uplink data (and may furthertrigger another STA to send uplink data).

If each STA is allowed to perform data transmission in all of theforegoing three manners, when there are many STAs, a large quantity ofusers may participate in CSMA/CA contention or OFDMA contention, aprobability of a collision between users is greatly increased, andchannel utilization is decreased. Embodiments of the present inventionprovide a channel access manner management mechanism, so as to decreasea congestion degree of a system and improve the channel utilization.

Embodiment 1: Multi-User Transmission Framework

When multiple users perform random access, an AP needs to provide atrigger frame, to ensure that signals of the multiple users reach the APin an aligned manner. A basic process is as follows:

Step 1: The AP sends a trigger frame, and the trigger frame is used totrigger a station to perform OFDMA-based random access.

Step 2: The station determines, according to a sending condition,whether to send a random access packet. If the station determines tosend a random access packet, the station sends the random access packetin a specified time after receiving the trigger frame.

The sending condition may be one or more of the following:

(1) The station generates a random backoff number (random backoffnumber) within a contention window range for a to-be-sent packet, andthe station updates the random backoff number according to a quantity ofresources for random access that are included in the trigger frame, anddetermines to send the random access packet if backoff is completed.Updating the random backoff number includes: a new random backoffnumber=an original random backoff number−the quantity of resources forrandom access. If the random backoff number reaches 0, backoff iscompleted.

(2) The station generates a random backoff number (random backoffnumber) within a contention window range for a to-be-sent packet, andthe station updates the random backoff number according to an accesscondition included in the trigger frame and a quantity of resources forrandom access that are corresponding to the access condition and thatare included in the trigger frame, and determines to send the randomaccess packet if backoff is completed. Updating includes: a new randombackoff number=an original random backoff number−the quantity ofresources for random access. If the random backoff number reaches 0,backoff is completed.

The sending condition may include a requirement for a type (anassociation request, a buffer size report (Buffer Size Report), anidle/available channel report, a channel status report, or a channelquality/signal to interference plus noise ratio report) of the randomaccess packet of the station, and/or a requirement for a service type ofthe random access packet.

The sending condition may further include whether the station needs todetermine, when performing access, whether a channel is busy or idle.The station accesses a channel only when the channel is idle or thestation updates the random backoff number only when a channel is idle.

It should be noted that a packet and a frame in the embodiments of thepresent invention may be interchangeably used unless otherwisespecified.

Step 3: The AP sends an acknowledgement frame after receiving a randomaccess packet of one or more stations. The acknowledgement frameincludes acknowledgement indication information about that the APsuccessfully receives the random access packet.

Step 4: The station receives the acknowledgement frame, and learns,according to the acknowledgement indication information, whether therandom access packet sent by the station is successfully received by theAP.

During implementation, the AP may also be a common station in a network.

FIG. 1 is a schematic flowchart of a frame exchange of STA randomaccess. In this process, if a quantity of stations that meet the sendingcondition is greater than one, the stations may send the random accesspacket (such as a packet sent by a STA 1, a STA 2, or a STA 3 in FIG. 1)in parallel. FIG. 2 is a schematic diagram of a basic structure of anuplink random access packet. When the OFDMA-based access manner is used,a specific format of the random access packet sent by the station isshown in FIG. 2. A signal (such as an L-STF (Legacy Short TrainingField, legacy short training field) before high efficiency-shorttraining field (English: High Efficient-Short Training Field, HE-STF forshort), an L-LTF (Legacy Long Training Field, legacy long trainingfield), an L-SIG (Legacy Short Training Field, legacy short trainingfield), an RL-SIG (Repeat Legacy Short Training Field, repeat legacyshort training field), an HE-SIG-A (High Efficiency Signal Field, highefficiency signal field A), or an HE-SIG-B (High Efficiency SignalField, high efficiency signal field B)) is used for a receive end todetect a packet start event, synchronization, or channel estimation, andindicate a packet format. If the packet format is a high efficiency(English: High Efficient, HE for short) packet format, a quantity ofsymbols of the high efficiency long training field HE-LTF is furtherindicated. The station sends an HE-STF signal and an HE-LTF signal on asub-channel to provide a channel estimation reference. Optionally, thestation may send a load signal after the HE-LTF signal.

The receive end receives and parses the HE-STF front signal, the HE-STFfront signal indicates the quantity of symbols of the HE-LTF and apacket length, and time of data load or a quantity of symbols of thedata load may be obtained according to the packet length. The receiveend receives the HE-STF signal so that the receive end adjusts andsynchronizes automatic gain control (Automatic Gain Control, AGC). Thenthe receive end receives the HE-LTF signal, and the receive end mayperform channel estimation based on the HE-LTF signal. If packet lengthinformation indicates that there is data load, the receive end continuesto receive the data load. The HE-LTF signal may be a row or a column ina P-matrix or a row or a column in another orthogonal matrix, and may beselected from a set including a low correlation sequence.

Based on the received HE-LTF signal, the receive end may determinewhether an HE-LTF sequence on a sub-channel is used and/or determinecorresponding received signal strength. Specifically, the receive endperforms channel estimation based on the received HE-LTF signal toobtain a channel coefficient h, and the channel coefficient may be aplural (for example, when there is a single receive antenna) or may be avector (for example, when there are multiple receive antennas). Areceived signal power value may be obtained by performing modulooperation on h and calculating a square value or performing anothermathematical operation. The received signal power value depends on achannel gain and a transmit signal power of a sender. It may bedetermined, according to the received signal power value, whether theHE-LTF sequence on the sub-channel is used. When the power value ishigher than a specified threshold, the receive end may determine thatthe HE-LTF sequence on the sub-channel is used. A physical layer of thereceive end may add a receive vector (rxvector) message in a receivestart indication (RXstart indication), so as to report a receivingresult of the HE-LTF to a MAC layer. Specifically, the receiving resultmay include a detection result on a subcarrier/sub-channel/spatialflow/LTF sequence. Optionally, the detection result may be whether theHE-LTF sequence is used or the corresponding received signal strength.

Further, the receive end may set a threshold based on noise powerstrength or noise plus interference strength existing before an uplinkpacket is received. Alternatively, some sub-channels and/or HE-LTFsequences may be reserved when sub-channels and HE-LTF sequences areallocated. The receive end may set the threshold by measuring noisepower strength or noise plus interference strength on these reservedresources. A success rate, a false detection rate, or an omission rateof determining whether an HE-LTF sequence is used may be controlled byadjusting the threshold.

Embodiment 2

This embodiment provides an access method, including:

sending, to an AP, a first frame that carries uplink transmissionrequirement information; and

if a second frame that carries uplink transmission indicationinformation is received from the AP within an agreed time period, andthe uplink transmission indication information includes a resourceindication and a transmission manner indication, sending uplinkmulti-user transmission data to the AP, where multiple uplink userstransmit, according to a transmission manner (including a modulation andcoding scheme or transmission duration) indicated by the transmissionmanner indication, to-be-transmitted data on an uplink transmissionresource indicated by the resource indication; or if the second frame isnot received within an agreed time period, accessing, by a station, achannel in a CSMA/CA-based contention access manner.

The first frame may be sent in the CSMA/CA-based contention accessmanner or by using an OFDMA access method. The uplink transmissionrequirement information includes a packet arrival interval, packet sizeinformation, or traffic rate information. In addition, the uplinktransmission requirement information may further include a flow rate,bandwidth requirement information, or a BSR. After receiving anacknowledgement frame or a response frame of the AP corresponding to thefirst frame, the station may suppress an access manner of CSMAcontention access, including increasing a contention window parameter ofthe CSMA contention access, or stopping backoff number updating of theCSMA contention access, or forbidding the CSMA contention access. Thisimplementation may decrease a probability of a contention transmissionattempt of the station, thereby increasing a probability that the accesspoint succeeds in transmission contention. The access point may instructmultiple users to perform concurrent transmission after the contentionis successful, thereby improving channel access efficiency.

The AP provides an uplink transmission resource to the station by usingthe second frame. Specifically, the second frame may be a trigger frame.In addition, the agreed time period may be a duration having a specifictime length. The agreed time period may be counted. The AP may addtarget sending time and/or a timeout duration indication of the secondframe to the acknowledgement frame or the response frame to the firstframe or in a beacon frame. The station obtains the agreed time periodaccording to the target sending time and timeout duration. The agreedtime period=the target sending time+the timeout duration. The timeoutduration may further be agreed in a protocol. The station may furtheruse time at which the acknowledgement frame or the response frame of theAP to the first frame is received plus the timeout duration as theagreed time period.

Embodiment 3

The access method provided in Embodiment 2 may use multiple differentscenarios. Accordingly, this embodiment provides, corresponding to thedifferent scenarios (or different data transmission types or differentservice transmission types), a process of implementing access by meansof interaction between an AP and a STA. Details are as follows:

Scenario 1: Periodic and Constant-Rate Data Transmission

For example, the scenario is applicable to a voice service with mutesuppression disabled. A voice service packet periodically arrives, and acoding rate of the voice service determines a packet size.

As shown in FIG. 3A, after receiving a first frame that is sent by theSTA and that carries uplink transmission requirement information, the APsends, to the STA at a preset first time point, a first trigger framethat carries information about an uplink transmission resource, and theSTA performs uplink multi-user data transmission according to anindication of the first trigger frame. The AP sends, to the STA at apreset second time point, a second trigger frame that carries theinformation about the uplink transmission resource, and the STA performsuplink multi-user data transmission according to an indication of thesecond trigger frame. The first trigger frame and the second triggerframe are equivalent to the second frame in Embodiment 2, and there maybe multiple second frames.

A period in the scenario may be an absolute agreed time period or may bea non-absolute agreed time period. When this embodiment of the presentinvention is applied to a system in which carrier sense needs to beperformed, if the AP detects that a channel is busy, the AP delayssending, and directly performs sending after the channel is idle orperforms sending after backoff is completed. Therefore, sending time ofthe trigger frame may be later than the agreed time period, and theagreed time period is called the non-absolute agreed time period, and iscalled the absolute agreed time period in another case.

The STA may start a periodic and constant-rate data transmission timerin the agreed time period (for example, the first time point and thesecond time point in FIG. 3A) of the trigger frame to handle withtimeout. If the STA receives the trigger frame in a preset condition(including before the periodic and constant-rate data transmission timertimes out), the STA may cancel the timer. If the trigger frame is notreceived in the preset condition, the STA may access a channel by usinganother method.

For example, the scenario 1 is further applicable to a voice servicewith a variable rate. A voice service packet periodically arrives, andthe voice service uses variable rate coding, leading to a variablepacket size. After transmission of the first packet is completed, ifthere is subsequent data to be transmitted, the STA may request the APto allocate more resources.

Specifically, after receiving the first trigger frame, the STA performsuplink multi-user data transmission according to the indication in thefirst trigger frame (it should be noted that in this embodiment of thepresent invention, there may be one or more STAs that perform uplinkmulti-user data transmission), and the first trigger frame indicates aparameter such as a frequency band or transmission time of uplinkmulti-user data transmission of the STA. If a quantity of resourcesallocated by the AP is less than that required by the STA, the STA mayadd a bandwidth indication (or a remaining buffer size non-zeroindication, that is, a buffer has data to be transmitted) in uplinkmulti-user data transmission. If the bandwidth indication bit is 1, itrepresents that the STA needs more uplink resources, and the AP mayprovide, in a subsequent trigger frame, an uplink multi-user datatransmission resource indication to the STA. As shown in FIG. 3B, afterthe first trigger frame is sent and before the second trigger frame issent, the AP may continue to send a trigger frame to the STA, and thetrigger frame indicates a resource for further uplink multi-user datatransmission. In this way, if the quantity of resources previouslyallocated by the AP is less than that required by the STA, the STA maycontinue to perform uplink multi-user data transmission on the uplinkmulti-user data transmission resource indicated by the trigger frame.

Scenario 2: Aperiodic and Equal-Size Data Transmission

After receiving a first frame that is sent by the STA and that carriesuplink transmission requirement information, the AP sends a null datatrigger frame to the STA, and the null data trigger frame includes anagreed time period. The agreed time period may be a time relative to abeacon frame of the AP, or a periodic time, or a combination of both.The AP receives a reply of the STA to a null data trigger frame 1.According to the reply, the AP sends a trigger frame to provide anuplink multi-user data transmission resource to the STA.

As shown in FIG. 3C, the AP sends the null data trigger frame 1. Afterreceiving the null data trigger frame 1, the STA performs uplinktransmission and may include an agreed sequence (for example, an LTFsequence or an LTF sequence on a specific sub-channel) in an uplinktransmission frame. The sequence may be included in the null datatrigger frame 1 and specified by the AP, or may be specified by the APwhen the STA and the AP are associated.

The AP receives the sequence on a specific sub-channel. If the sequenceis a sequence agreed with a STA, the AP sends the first trigger frame tothe STA, and the first trigger frame carries information about an uplinkmulti-user data transmission resource that is allocated by the AP to theSTA according to packet size information or traffic rate information.After receiving the first trigger frame, the STA performs uplinkmulti-user data transmission according to the uplink multi-user datatransmission resource indicated by the first trigger frame.

When the beacon frame indicates the agreed time period of the null datatrigger frame, or the AP and the STA negotiate the agreed time period ofthe null data trigger frame, the STA may start a null data trigger frametimer in the agreed time period (for example, a first time point in FIG.3C) of the null data trigger frame. If receiving the null data triggerframe in a preset condition (including before the periodic andconstant-rate data transmission timer times out), the STA may cancel thetimer.

The station may start an uplink data scheduling transmission timer. Ifthe first trigger frame (or a second frame that carries informationabout an uplink transmission resource) is received in the presetcondition (including before the uplink data scheduling transmissiontimer times out), and uplink data transmission resource allocationinformation of the STA is included, the STA may cancel the timer. If thetrigger frame is not received in the preset condition, the STA mayaccess a channel by using another method.

Scenario 3: Periodic and Variable-Rate Data Transmission

As shown in FIG. 3D, after receiving a first frame that is sent by theSTA and that carries uplink transmission requirement information, the APmay contend for a channel and send a trigger frame 1 after contentionbackoff is completed. After receiving the trigger frame 1, the STA mayinclude buffer status report information or bandwidth requestinformation in uplink multi-user data transmission. After the APreceives a request of the STA, the AP sends a trigger frame 2, and thetrigger frame 2 indicates an uplink multi-user data transmissionresource that is allocated by the AP to the station according to theuser request. After receiving the trigger frame 2, the STA performsuplink multi-user data transmission according to the uplink multi-userdata transmission resource indicated by the trigger frame.

Scenario 4: Aperiodic and Variable-Size Data Transmission

As shown in FIG. 3E, after receiving a first frame that is sent by theSTA and that carries uplink transmission requirement information, the APmay contend for a channel and send a trigger frame 1 after contentionbackoff is completed, and the trigger frame 1 indicates a quantity ofspatial flows or a quantity of LTF symbols or a sequence length foruplink transmission. After receiving the trigger frame 1, the STA mayinclude an agreed sequence (for example, an LTF sequence or an LTFsequence on a specific sub-channel) in an uplink transmission frame 1.

The AP receives the sequence on a sub-channel, and if the sequence is asequence agreed with a STA, the AP sends a trigger frame 2. The triggerframe 2 may include a received sequence number or a sub-channel number,or a number jointly determined by the sequence number and thesub-channel number, and the AP instructs a STA corresponding to thenumber to send buffer status report information or bandwidth requestinformation. Alternatively, the trigger frame 2 carries a stationidentifier, and the AP instructs a STA having the station identifier tosend buffer status report information or bandwidth request information.

After receiving the trigger frame 2, the STA sends, according to anindication of the trigger frame 2, an uplink transmission frame 2 thatcarries a bandwidth request, and the uplink transmission frame 2includes buffer status report information or bandwidth requestinformation. After receiving the uplink transmission frame 2, the APsends a trigger frame 3 according to the uplink transmission frame 2 toallocate an uplink resource to the STA. After receiving the triggerframe 3, the STA performs uplink multi-user data transmission accordingto the uplink multi-user data transmission resource indicated by thetrigger frame 3.

Scenario 5: Aperiodic and Low-Delay Data Transmission

As shown in FIG. 3F, the STA may report existence of aperiodic andlow-delay data transmission to the AP. The AP sends a trigger frame forrandom access, and the trigger frame indicates uplink multi-user datatransmission resource allocation. At least one uplink resource (forexample, an OFDMA sub-channel) is used for random access. Afterreceiving the trigger frame, the station selects an uplink resource toperform uplink random access, or chooses to not perform uplink randomaccess.

FIG. 3G-1 and FIG. 3G-2 are schematic diagrams in which multipletransmission manners jointly work. As shown in FIG. 3G-1 and FIG. 3G-2,multiple transmission manners that are applicable to different scenariosmay jointly work. When data of different types needs to be transmitted,according to a scenario to which the data is applicable, a correspondingtransmission manner may be selected or multiple transmission manners maybe selected at the same time to perform transmission.

Embodiment 4

This embodiment provides an access method, including:

receiving, from an AP, a first frame that carries information about anuplink transmission resource;

sending, to the AP, a second frame that carries uplink transmissionrequirement information, and disabling a CSMA/CA-based contention accessmanner or suspending a CSMA/CA contention access backoff timercorresponding to an uplink transmission requirement information queue;and

if a third frame that carries information about an uplink transmissionresource is received from the AP within an agreed time period, sendinguplink multi-user transmission data to the AP, where the uplinkmulti-user transmission data is transmitted on the uplink transmissionresource; or if the third frame is not received within an agreed timeperiod, enabling, by a station, the CSMA/CA-based contention accessmanner to access a channel or resuming the CSMA/CA contention accessbackoff timer corresponding to the uplink transmission requirementinformation queue.

The information about the uplink transmission resource in the thirdframe may further include an identifier of one or more stations that usethe uplink transmission resource. The backoff timer may further be abackoff counter.

The uplink transmission requirement information includes whether the STAhas data to be sent, and this may be indicated by using one bit.Multiple STAs may simultaneously send the second frame that carries theuplink transmission requirement information (training parts of thesecond frames may be the same or overlap, and load parts of the secondframes may not overlap). In addition, disabling or enabling theCSMA/CA-based contention access manner may be disabling or enabling aCSMA/CA-based contention access function by the STA. The third frame maybe a trigger frame.

FIG. 4 is a schematic flowchart of a frame exchange of the access methodaccording to Embodiment 4 of the present invention. As shown in FIG. 4,the AP sends, to the STA, the first frame (for example, a data frame ora trigger frame is used to carry indication information) that carriesthe information (which may be considered as the indication information,such as indication information in FIG. 4) about the uplink transmissionresource. The indication information indicates the uplink transmissionresource that can be allocated to the STA to perform uplink multi-usertransmission (that is, the access point notifies, by using the firstframe, the station that there is an available uplink transmissionresource, and the access point instructs, by using the first frame, anyuser to respond to the first frame without requiring backoff). The STAthat needs to perform uplink multi-user data transmission may send theuplink transmission requirement information according to the indicationinformation. The AP may further indicate, according to the indicationinformation, a parameter for the STA to perform uplink multi-user datatransmission (for example, indicate an uplink transmission resource, ause manner, or a sub-channel that is used by the STA, allocation of aspatial flow, or a modulation and coding scheme). The STA generates,according to the parameter, the second frame (for example, a frame thatcarries 26-tone RU information) that carries the uplink transmissionrequirement information. Because all STAs use a same parameter,generated second frames are the same. Therefore, although multiple usersuse a same resource to transmit the frame, the signals of the multipleusers do not interfere with each other, and the AP may receive one ormore second frames (which may be multiple overlapped second frames).After receiving the second frame, the AP may send the third frame (forexample, the trigger frame for random access). If the AP does not occupya TXOP or a third frame exchange cannot be completed in a remaining TXOPtime, the AP may contend for a channel and send the third frame aftercontention backoff is completed. If the AP occupies a TXOP, the AP maysend the trigger frame. After receiving the trigger frame, the STAperforms uplink multi-user data transmission according to the triggerframe.

Table 1 lists three technical solutions for triggering datatransmission. In a technical solution 1, a specific user is specified toperform sending on a specific resource (the station does not need toperform contention backoff). In a technical solution 2, any user isspecified to perform random sending within a specific resource range. Inthe technical solution provided in this embodiment, any user isspecified to perform sending on a specific resource. It should be notedthat after receiving the second frame, the AP is allowed to triggermulti-user data transmission. For example, the AP may trigger multi-userdata transmission by using the technical solution 1 or 2 in table 1.

TABLE 1 Comparison between the solution provided in this embodiment andanother solution Technical solution 1: OFDMA Specific user Specificresource scheduling manner Technical solution 2: OFDMA Any user One ormore resources (the contention manner station needs to performcontention backoff) Technical solution in this Any user Specificresource (the station embodiment does not need to perform contentionbackoff)

Embodiment 5

When initially accessing an AP, a STA may determine a channel accessmanner according to an instruction of the AP, or may negotiate thechannel access manner with the AP, or the channel access manner may bepredetermined in a protocol.

Specifically, when initially accessing a channel, the STA learns, byreceiving a beacon frame, the channel access manner for accessing theAP. If the AP provides no indication, a default channel access manner(for example, the default access manner is a CSMA/CA-based contentionaccess manner) is used. The STA sends an association request frame tothe AP. The association request frame carries information about achannel access manner supporting capability/policy of the STA or about aversion of the station, and the information represents a defaultsupporting capability of the STA. Alternatively, the AP obtains thedefault supporting capability of the STA according to a format (forexample, a frame version/modulation and coding scheme) of theassociation request frame. After receiving the association requestframe, the AP sends an association response frame to the STA. Theassociation response frame carries a channel access policy (for example,carries information that indicates a channel access manner used by theSTA to access a channel). The STA accesses the channel according to thechannel access policy.

For example, when a STA performs initial access, the AP may specify anaccess manner for the STA according to information (for example, anaccess manner or a quantity of connected STAs) about a currentlyconnected STA. When there are many connected STAs, an OFDMA-basedscheduling access manner may be used.

Embodiment 6

This embodiment provides a timer design and timeout processing in anaccess process, for example, timing processing about an agreed timeperiod in each embodiment of the present invention. Details are asfollows:

FIG. 5 is a schematic diagram of several situations in which a timerneeds to be used. As shown in FIG. 5, in a case with an overlappingbasic service set (English: Overlapping Basic Service Set, OBSS forshort), if an AP is within a coverage area of the OBSS, the AP backs offwhen detecting that a channel is busy, and trigger frame sending in theagreed time period is delayed. After the channel is idle, the APcontends for the channel and sends a trigger frame after obtaining thechannel by means of contention.

If a STA is within the coverage area of the OBSS, the AP completesbackoff if not detecting that the channel is busy, and the AP sends atrigger frame. Because the STA is affected by transmission interferenceor noise or another environment factor in the OBSS, the STA continueswaiting if the STA fails to receive the trigger frame of the AP.However, because the AP has sent the trigger frame, and the STA may notreceive the trigger frame of the AP, the STA needs to actively performEDCA contention.

If both the AP and the STA are within the coverage area of the OBSS, theAP suspends counting of a backoff count if detecting that a channel isbusy and does not resume the counting of the backoff count until thechannel is idle. After backoff is completed, the AP sends the triggerframe. Because the STA can monitor transmission of the OBSS, the STA mayinfer that the AP delays the trigger frame sending because of the OBSS.The STA may wait for longer time, that is, the STA may consider, duringwaiting, a transmission delay caused by the ODSS.

Specifically, the STA may set a timer (or a backoff counter) at agreedtrigger frame arrival time, or may set a timer (or a backoff counter)after receiving an uplink packet or after a queue of the STA changesfrom empty to non-empty.

FIG. 5A is a schematic working diagram of a first timer according to anembodiment of the present invention. As shown in FIG. 5A, when the STAhas uplink data to be transmitted or a queue of the STA changes fromempty to non-empty, the STA or the queue starts a countdown. A durationof the countdown may be specified by the AP or agreed in a protocol.

FIG. 5B is a schematic working diagram of a second timer according to anembodiment of the present invention. As shown in FIG. 5B, after the STAreceives an uplink packet or a queue of the STA changes from empty tonon-empty, the STA or the queue sets a backoff number. The backoffnumber may be specified by the AP or agreed in a protocol. When thechannel is idle, the backoff number progressively decreases.Specifically, the backoff number may progressively decrease by one aftereach unit of time passes. When the channel is busy, progressivedecreasing of the backoff number is suspended.

FIG. 5C is a schematic working diagram of a third timer according to anembodiment of the present invention. As shown in FIG. 5C, after the STAreceives an uplink packet or a queue of the STA changes from empty tonon-empty, the STA or the queue sets a backoff number. The backoffnumber may be specified by the AP or agreed in a protocol. When thechannel is idle, the backoff number progressively decreases.Specifically, the backoff number may progressively decrease by one aftereach unit of time passes. When the channel is busy, progressivedecreasing of the backoff number is suspended. Further, when receiving atrigger frame for uplink random access sent by the AP, the STA updatesthe backoff number, for example, increases the backoff number. Receivingthe trigger frame represents that the AP has an intention to triggermultiple users to perform uplink transmission. The AP obtains a channelby means of contention to send the trigger frame for uplink randomaccess. To improve a probability that the AP obtains a channel by meansof contention, the STA actively decreases intensity of contending for achannel by the STA. Specifically, the STA may add a constant on thebasis of a current backoff number, and the constant is preset in aprotocol or is specified by the AP in a message frame (for example, anassociation response frame or a beacon frame). Alternatively, a currentbackoff number may be multiplied by a constant. The constant is presetin a protocol or is specified by the AP in a message frame.

FIG. 5D is a schematic working diagram of a fourth timer according to anembodiment of the present invention. As shown in FIG. 5D, when the STAperforms uplink transmission, for example, sends a buffer size report ora bandwidth request, and receives an acknowledgement frame of the AP forsuccessful transmission, the STA may update a backoff number. Becausethe STA has sent, to the AP, an amount of data that needs to betransmitted or required bandwidth information, the AP allocates aresource to the STA. Therefore, the STA may decrease, by updating thebackoff number, intensity of contending for a channel by the STA, so asto increase an AP scheduling opportunity.

Embodiment 7

After a STA obtains a channel, the STA may hand over a control right toan AP, and the AP instructs one or more STAs to perform uplinkmulti-user data transmission.

FIG. 6A is a first schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention. As shown in FIG. 6A, the STA accesses the channel in an EDCAmanner and sends a single-user physical layer protocol data unit(English: Physical layer Protocol Data Unit, SU-PPDU for short). Afterthe AP receives the uplink SU-PPDU sent by the STA, the AP replies withan acknowledgement frame or a block acknowledgement frame. The AP mayindicate, in the frame, that the AP is to send a multi-user transmissiontrigger frame by using a control channel. For example, the AP mayindicate, in the frame by using 1 bit, that the AP is to send amulti-user transmission trigger frame by using a control channel. Afterthe STA receives the frame, if it is indicated in the frame that the APis to send a multi-user transmission trigger frame by using a controlchannel, the STA may send an acknowledgement frame (the acknowledgementframe is used to confirm that the AP can send, by using a controlchannel, a frame for triggering uplink multi-user data transmission).Otherwise, the STA continues to send the uplink SU-PPDU.

The AP sends a multi-user transmission trigger frame after receiving theacknowledgement frame of the STA. The AP may include, in the triggerframe, information about an uplink transmission resource of the STA orof the STA and another STA. After the acknowledgement frame of the STAis received, the trigger frame may be sent after a SIFS time.

Optionally, after receiving the acknowledgement frame of the STA, the APmay send the multi-user transmission trigger frame after an interval ofduration 1 (an agreed time period longer than a SIFS). During the time,the AP detects a busy or idle state of the channel. If the channel isidle, the AP sends the multi-user transmission trigger frame. If thechannel is busy, the AP sends a short packet whose transmission time isshorter than a threshold, the short packet may be an acknowledgementframe or another short frame, and the STA may continue to use thechannel after receiving the short packet. Alternatively, if the channelis busy, the AP may not send a data packet. When the STA does notdetect, during duration 2 (for example, a time longer than the duration1), that the channel is busy or there is a packet to be sent, the STAmay continue to send a data packet.

FIG. 6B is a second schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention. As shown in FIG. 6B, the AP sends an acknowledgement frame ora block acknowledgement frame after receiving an uplink SU PPDU, andsends a multi-user transmission trigger frame after a SIFS time.Compared with the method shown in FIG. 6A, the AP may directly trigger,after sending the acknowledgement frame or the block acknowledgementframe, the STA to perform uplink multi-user data transmission without aneed of waiting to receive an acknowledgement frame replied by the STA.

Optionally, FIG. 6C is a third schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention. As shown in FIG. 6C, the AP sends an acknowledgement frame ora block acknowledgement frame after receiving an uplink SU-PPDU, and theacknowledgement frame carries uplink transmission trigger information.In this case, the AP does not need to indicate, in the frame by using 1bit, that the AP is to send a multi-user transmission trigger frame byusing a control channel. After one or more STAs receive the information,the STA sends uplink multi-user transmission data according to theuplink transmission trigger information.

FIG. 6D is a fourth schematic diagram of sending a multi-usertransmission trigger frame according to an embodiment of the presentinvention. As shown in FIG. 6D, the STA sends an RTS packet and the APreplies with a CTS packet. The AP may indicate, by using the CTS packet,whether a multi-user transmission trigger frame needs to be sent byusing a control channel.

If the AP needs to send a multi-user transmission trigger frame by usinga control channel, for a STA that supports this interaction process (forexample, a STA that supports a protocol version, or a STA that notifiesthe AP that the STA supports this interaction process, or a STA thatsupports handing over a channel control right), the AP may fill a MACaddress of the AP in a receive address (RA) field of the CTS. Otherwise,the AP may fill a MAC address of an RTS sender in the RA of the CTS.After the STA receives the CTS, if an RA address carried in the CTS isan address of the AP, the STA sends a short packet (for example, anacknowledgement frame), and the AP sends a multi-user transmissiontrigger frame after receiving the short packet. The AP may include, inthe multi-user transmission trigger frame, uplink transmission resourceindication information of the STA or of the STA and another STA. The STAperforms data transmission according to the uplink transmission resourceindication information after receiving the multi-user transmissiontrigger frame.

Embodiment 8

This embodiment of the present invention proposes an access manner (forexample, the foregoing three uplink access manners) of a STA, and theaccess manner may be specified by an AP. After the AP specifies anaccess manner to the STA, the STA can perform access and datatransmission in only the access manner specified by the AP. The AP mayspecify an access manner by sending a radio frame to the STA. The radioframe may carry indication information that is used to indicate theaccess manner of the STA. The radio frame may be a beacon frame or anassociation response frame.

Specifically, this embodiment proposes an access method, including:

receiving a radio frame sent by an AP, wherein the radio frame indicatesan access manner for performing channel access, and the radio frame isan association response frame, a beacon frame, or a response frame ofthe AP to a received data frame; and

if a second frame (for example, a trigger frame) that carriesinformation about an uplink transmission resource is received from theAP within an agreed time period, sending uplink multi-user transmissiondata to the AP, where the uplink multi-user transmission data istransmitted on the uplink transmission resource; or if the second frameis not received within an agreed time period, accessing, by a station, achannel in a CSMA/CA-based contention access manner.

If the radio frame is a beacon frame, a specific process of thisembodiment is as follows:

Step 1: The AP generates the beacon frame, and the beacon frame carriesindication information that is used to indicate an access manner of theSTA.

Step 2: The AP sends the beacon frame.

The indication information in step 1 may be public information shared byall STAs, or may be private information dedicated for one or more STAsand separately indicating a transmission manner to each STA. For thelatter, the beacon frame may further include an identifier (for example,an association identifier AID) of the one or more STAs.

The indication information sent to each STA may be a field. A value ofthe field may indicate one or more transmission manners that can be usedby the STA. The indication information may further be a bitmap (bitmap).Each bit may indicate whether a transmission manner is allowed to beused.

If the radio frame is an association response frame, a specific processof this embodiment is as follows:

Step 1: The STA sends an association request frame to the AP.

Step 2: The AP sends an association response frame to the STA, and theassociation response frame includes indication information that is usedto indicate an access manner of the STA.

In addition, the association request frame and the association responseframe in step 1 and step 2 may further be a re-association request frameand a re-association response frame. Processes are the same, and detailsare not described herein again.

Embodiment 9

According to an access manner used by a STA, there are three datatransmission states of the STA:

Contention state: The STA can perform data transmission only in acontention-based manner, for example, the manner 1 and/or the manner 2in the foregoing three access manners.

Scheduling state: The STA can perform data transmission only in ascheduling-based manner, for example, the manner 3.

Hybrid state: The STA can perform data transmission in both acontention-based manner and a scheduling-based manner, for example, anyone of the manner 1, the manner 2, or the manner 3.

The AP specifies an access manner to the STA, and this is actuallyallocating a data transmission state to the STA. However, the datatransmission state of the STA may need to change with time. For example,when there are few STAs in a system, the hybrid state of the STA is moreconducive to sending data of the STA. When there are many STAs, thecontention state or the scheduling state of the STA helps improveoverall system performance. Therefore, this embodiment proposes a methodfor switching a data transmission state of a STA.

When the STA is in a data transmission state and successfully sends adata frame to an AP, the AP sends a response frame to the STA, and theresponse frame carries indication information that is used to indicate adata sending manner of the STA (or enable the STA to enter a datatransmission state). A specific process is as follows:

Step 1: The STA sends a radio frame to the AP. The radio frame may be adata frame.

Step 2: The AP sends a response frame to the STA, and the response framecarries indication information that is used to indicate a data sendingmanner of the STA.

When the STA is in the contention state and successfully sends a dataframe to the AP, and the AP discovers that there are many STAs in asystem at this time, because excessive contention-state STAs greatlyaffect the overall system performance, the AP sends, in a responseframe, indication information to the STA, so that the STA enters thescheduling state, thereby decreasing a contention degree inside thesystem and improving overall channel resource utilization.

Alternatively, the AP may enable, by using the indication information,the STA to enter the hybrid state from the contention state. The STAshould monitor a channel to receive a trigger frame, or preferablychoose to send a buffer status report BSR instead of directly sending adata frame.

Similarly, the AP may further enable, by using the indicationinformation, the STA to enter the contention state from the hybridstate. In this case, the STA can send data only in the manner 1 and/orthe manner 2, and this affects contention access policy selection by theAP.

It should be noted that step 1 in the foregoing process may be omitted,that is, the AP directly sends a radio frame to the STA, and the radioframe carries indication information that is used to indicate a datasending manner of the STA.

In addition, the STA may determine a transmission mode according to aspecific rule when no indication information is received. For example,the STA uses an OFDMA-based scheduling access manner by default.Optionally, if the STA uses the OFDMA-based scheduling access manner, atimer may be set. After the timer times out, the STA may use aCSMA/CA-based contention access manner or an OFDMA-based contentionaccess manner.

Embodiment 10

The OFDMA-based contention access manner is that an AP sends a triggerframe for random access (English: Trigger Frame for Random access, TFRfor short) and specifies one or more sub-channels in the TFR for randomaccess. After receiving the TFR, when a condition is met (or when acondition for responding to the TFR is met), a STA may randomly select asub-channel for random access to perform transmission. Because the STArandomly selects a sub-channel, a probability of a collision isrelatively large. Analysis shows that highest channel utilization ofthis method is about 37%. When a large quantity of STAs jointlyparticipate in contention, channel utilization may be lower. Therefore,this embodiment provides the following three data sending methods.

Method 1: After the STA receives the TFR and when the condition is met:

the STA sends an unfragmented data frame (for example, an unfragmentedMAC layer protocol data unit (English: MAC layer Protocol Data Unit,MSDU for short)) within a time specified by the TFR; or

if the STA sends, within a time specified by the TFR, an aggregated MPDUthat includes multiple MPDUs, the multiple MPDUs include a maximum ofone fragmented data frame, for example, only the last MPDU includes afragmented data frame.

Method 2: After receiving the TFR, the STA is not allowed to send a dataframe unless the data frame carries a buffer status report BSR.

Method 3: After receiving the TFR, the STA is not allowed to send a dataframe.

Embodiment 11

For the OFDMA-based scheduling access manner, after receiving a triggerframe sent by an AP, a STA may perform data transmission on acorresponding channel according to an indication of the trigger frame.Before the AP sends the trigger frame to the STA, the STA needs to senda buffer status report BSR to the AP. The BSR may be sent in theCSMA/CA-based contention access manner (manner 1) or in the OFDMA-basedcontention access manner (manner 2). In view of a problem about whetherthe STA is allowed to send the BSR (or another control frame/managementframe) in the two contention access manners, this embodiment proposesthe following several feasible solutions.

Solution 1: The STA may perform sending in the manner 1 and the manner 2at the same time. That is, the STA may simultaneously enable two backoffprocesses, one is used for CSMA/CA-based contention access, and theother is used for OFDMA contention-based contention access.

Solution 2: The STA performs sending in either of the manner 1 and themanner 2, and the STA determines to select the manner 1 or the manner 2.

Solution 3: The AP specifies the STA to perform sending in the manner 1and/or the manner 2. That is, the AP sends a radio frame to the STA, theradio frame carries indication information, and the indicationinformation is used to specify the STA to perform sending in the manner1 or the manner 2 or both manners. The radio frame may be a beaconframe, an association response frame, or a re-association responseframe. For example, the AP includes, in the beacon frame, indicationinformation that indicates a sending manner of the STA, and the STAreads the beacon frame to obtain the sending manner, and sends anassociation request frame to the AP in the sending manner.

Embodiment 12

This embodiment proposes a transmission mode switching method. Afterobtaining a TXOP by obtaining a channel by means of contention in theCSMA/CA-based manner, a STA may send a radio frame to an AP and handover the TXOP to the AP. The AP may initiate uplink multi-usertransmission by using the TXOP and needs to schedule the STA in theuplink multi-user transmission. A specific process is as follows:

Step 1: The STA accesses a channel in the CSMA/CA-based contentionaccess manner, and sends a radio frame to the AP after contention issuccessful, where the radio frame carries indication information, theindication information is used to indicate that the AP may instruct,after receiving the radio frame, the STA to perform uplink multi-userdata transmission, and the AP needs to schedule the STA in the uplinkmulti-user transmission.

Step 2: After receiving the radio frame, the AP sends a trigger frameafter a preset time, where the trigger frame carries schedulinginformation for triggering the STA to send a data frame (in addition,another STA may be triggered).

Step 3: The STA sends a radio frame according to the trigger informationof the AP.

Step 4: The AP sends a multi-user block acknowledgement (English:multi-user block ACK, MBA for short) frame.

In addition, the STA may add indication information in the radio framein step 3, so as to indicate whether the AP can continue to send anotherframe after sending the MBA in step 4. The another frame may be atrigger frame or a downlink data frame. If the indication informationindicates that the AP can further continue to send another frame, aftersending the MBA in step 4, the AP sends a radio frame after a presettime. The preset time may be a SIFS, and the radio frame may be atrigger frame or a downlink data frame. If the indication informationindicates that the AP cannot continue to send another frame, aftersending the MBA in step 4, the AP cannot send a radio frame. The STA maysend a radio frame after a preset time, and the preset time may be aSIFS.

Embodiment 13

This embodiment provides a transmission mode switching method. Afterobtaining a TXOP by obtaining a channel by means of contention in theCSMA/CA-based contention access manner, a STA may send a radio frame toan AP, and the AP is allowed to schedule another STA to share the TXOPwith the STA. A specific sharing manner may be an OFDMA manner or amulti-user MIMO manner. As an owner of the TXOP, the STA has a right tocontrol whether a current TXOP is for multi-user transmission orsingle-user transmission, and control a transmission time of thesingle-user transmission or the multi-user transmission.

As shown in FIG. 7, this embodiment provides a transmission modeswitching method, including the following steps.

Step 1: A STA 1 sends, at a TXOP initiated by the STA 1, a first frameto an AP, where the first frame carries first indication information,and the first indication information is used to indicate that the AP maytrigger uplink multi-user data transmission.

Step 2: After receiving the first frame of the STA 1, the AP sends atrigger frame after a preset time.

The trigger frame should carry scheduling information for triggering theSTA to send a data frame (that is, ensuring that the STA is triggeredwhile another STA may further be triggered). The scheduling informationis used to: when an uplink multi-user MIMO (UL MU-MIMO) transmissionmanner is used, allocate a space-time stream to each uplink user; whenan uplink orthogonal frequency division multiple access (UL OFDMA)transmission manner is used, allocate a frequency domain sub-band toeach uplink user; and when the UL OFDMA and UL MU-MIMO transmissionmanners are used, allocate a frequency domain sub-band to each uplinkuser and a space-time stream of each user in the frequency domainsub-band.

The AP replies to the first frame (for example, sends an ACK frame or aBlock ACK (BA) frame) before sending the trigger frame or at the sametime when sending the trigger frame. Specifically, after the AP receivesthe first frame of the STA 1, a response frame replied by the AP maycarry second indication information, and the second indicationinformation is used to indicate whether the AP complies with anindication of the STA 1. That is, the AP may further use the secondindication information to refuse to use UL MU transmission, and mayreply to the first frame in a conventional manner.

Step 3: The STA 1 sends a second frame according to information carriedin the trigger frame sent by the AP. The second frame is sent in a UL MUformat. According to an indication of the trigger frame sent by the AP,the UL MU format may be a frame format of a user in UL OFDMA (that is,the second frame is located in a frequency domain sub-channel allocatedby the AP), or may be a format of a user in UL MU-MIMO (that is, thesecond frame is located in a spatial flow/space-time stream allocated bythe AP).

According to the indication of the trigger frame, in addition to the STA1, another STA (for example, a STA 2) and the STA 1 both use the UL MUmanner to send data to the AP.

Step 4: The AP sends a response frame, where the response framesimultaneously responds to data frames (or UL MU data frames) sent bymultiple users. The response frame may be a multi-user blockacknowledgement MBA (multi-user block ACK) frame or an acknowledgement(ACK/BA) frame carried in a DL MU (downlink multi-user) manner.

In addition, the STA may also add the first indication information inthe second frame in step 3 to indicate whether the AP can continue totrigger UL MU transmission in subsequent transmission. In addition, whensending the response frame, the AP may choose to use the DL MUtransmission manner to send data of more than one user to each user.Therefore, if the STA 1 is allowed to continue UL MU transmission instep 3, in step 4, the AP may respond to a multi-user data frame in step3 by using an independent trigger frame, or may respond with informationor a downlink multi-user data frame by using DL MU and carrying atrigger frame in the DL MU.

In this embodiment, if the first indication information in the framesent by the STA 1 indicates that the AP cannot trigger UL MUtransmission (unauthorized multi-user transmission indicated by a frame1-3 shown in FIG. 7), the AP cannot trigger UL MU transmission in asubsequently sent frame.

In this embodiment, transmission of the STA 1, the owner of the TXOP,determines a transmission length of the TXOP. Therefore, if transmissionof the STA 1 ends, and an unauthorized AP continues using the TXOP, theSTA 1 may send a contention free-end (English: Contention Free-End,CF-End for short) frame to end the TXOP. When the AP triggers more thanone STA to send data by using UL MU, a data length of the STA 1 shouldbe used as a reference of a transmission time, that is, transmission ofanother STA cannot exceed a transmission length of the STA 1.

The preset time in this embodiment may be a SIFS, or may be anotherfixed time, such as an SSIFS or PIFS. The first indication informationin this embodiment is located in an HE control field, the secondindication information may also be located in the HE control field, andan information bit of the first indication information may be evenreused.

In addition, in this process, if the STA 2 indicates, in a frame that isin the UL MU format and that is sent by the STA 2, that data sending isnot completed (for example, a more data bit is set to 1), the AP mayindicate, in a subsequent trigger frame, that sending of some data isnot completed (a specific form may be reusing the more data bit or maybe using another dedicated information bit). As the owner of the TXOP,the STA 1 may consider the information to determine whether to continueto allow UL MU transmission. When the AP triggers UL MU transmission,the STA 1 may indicate, while indicating UL MU transmissionauthorization, information about a minimum resource allocated to the STA1 in the authorized UL MU, so that the AP is prevented from allocatingfew resources to the STA 1, the owner of the TXOP. For example, if theAP triggers UL OFDMA transmission subsequently, the STA 1 may indicatethat a minimum bandwidth allocated by the AP to the STA 1 cannot be lessthan 20 MHz.

Embodiment 14

This embodiment of the present invention may be applied to a scenario ofmulti-user uplink contention.

When a station has a to-be-sent data packet or the station sends abuffer size report and receives an acknowledgement frame replied by anAP, there are three cases: 1. If a trigger frame is received within anagreed time period, an OFDMA access manner (which may be the OFDMAcontention access manner or the OFDMA scheduling access manner) is usedto send data, or if no trigger frame is received within an agreed timeperiod, the CSMA/CA-based contention access manner is used to send data.2. A CSMA/CA-based contention access manner whose CW is relatively largeis used within an agreed time period to send data, and a CSMA/CA-basedcontention access manner whose CW is relatively small is used after theagreed time period to send the data. 3. A size of a CW is decreased whenan agreed time period ends.

From a target sending time point that is of a trigger frame and that isindicated by a beacon frame or a target sending time point that is of atrigger frame and that is negotiated by a station and an AP, there arethree cases: 1. If a trigger frame is received within an agreed timeperiod, an OFDMA access manner (which may be the OFDMA contention accessmanner or the OFDMA scheduling access manner) is used to send data, orif no trigger frame is received within an agreed time period, theCSMA/CA-based contention access manner is used to send data. 2. ACSMA/CA-based contention access manner whose CW is relatively large isused within an agreed time period to send data, and a CSMA/CA-basedcontention access manner whose CW is relatively small is used after theagreed time period to send the data. 3. A size of a CW is decreased whenan agreed time period ends.

For the foregoing agreed time period, the station may set a timer tocount the agreed time period. A channel access method 1 (for example,(if a trigger frame is received) the OFDMA access manner or theCSMA/CA-based contention access manner whose CW is relatively large) isused before the timer times out. A channel access method 2 (for example,(if a trigger frame is received) the OFDMA access manner or theCSMA/CA-based contention access manner whose CW is relatively small) isused after the timer times out. The timer is canceled after a triggerframe from the AP is received. Before the timer times out, one way isthat the station delays contention or decreases intensity of contendingfor a channel by the station. In addition, when obtaining a channel bymeans of contention, the station may hand over a control right to theAP, and the AP sends a multi-user transmission trigger frame. Thetrigger frame may carry information about an uplink transmissionresource.

The station uses, upon an event 1, an access manner that suppresses CSMAcontention access. The station uses, upon an event 2, a manner thatpromotes CSMA contention access. The access manner that suppresses CSMAcontention access includes: to increase a contention window parameter ofCSMA contention access, or to stop backoff number updating of CSMAcontention access, or to disable CSMA contention access. The accessmanner that promotes CSMA contention access includes: to decrease acontention window parameter of CSMA contention access, or toresume/start backoff number updating of CSMA contention access, or toenable CSMA contention access.

The event 1 may be that the station has a to-be-sent data packet or thestation sends a buffer size report and receives an acknowledgement framereplied by the AP, or the like. The event 2 may be that the timer timesout and no trigger frame sent by the AP is received, or the like. The APprovides an event indication, and the event indication is used to(explicitly or implicitly) indicate the station to use a channel accessmanner. For example, the event indication may be the information aboutthe uplink transmission resource carried in the trigger frame sent bythe AP.

Embodiment 15

FIG. 8 shows an access apparatus according to an embodiment of thepresent invention. As shown in FIG. 8, this embodiment provides anaccess apparatus, including:

a sending module 801, configured to send, to an access point, a firstframe that carries uplink transmission requirement information; and

a processing module 802, configured to: if a second frame that carriesinformation about an uplink transmission resource is received from theaccess point within an agreed time period, send uplink multi-usertransmission data to the access point, where the uplink multi-usertransmission data is transmitted on the uplink transmission resource; orif the second frame is not received within an agreed time period,access, by a station, a channel in a contention access manner that isbased on carrier sense CSMA/CA.

Optionally, the access apparatus further includes a timing module 803,configured to count the agreed time period by using a timer, where aninitial value of the timer is specified by the access point or is agreedin a protocol.

Optionally, the access apparatus further includes a receiving module804, configured to receive a radio frame sent by the access point, wherethe radio frame indicates sending time of the second frame, and theradio frame is an association response frame, a beacon frame, or aresponse frame of the access point to a received data frame.

Some technical features in the foregoing apparatus embodiment, such asan access manner, the timer, or other further descriptions (such as atrigger frame), are similar or corresponding to some technical featuresin the foregoing method embodiments, and no repeated descriptions aregiven herein.

In addition, corresponding to the foregoing method, an embodiment of thepresent invention further provides an access apparatus. The apparatusincludes a memory and a processor, the memory is configured to store aninstruction required by the processor for execution, and the processoris configured to execute the method in the foregoing embodiments. Inaddition, the apparatus may further include a transmitter and a receiverthat are respectively configured to send and receive data.

According to the embodiments of the present invention, such asdescriptions herein, although the present invention is described inspecific embodiments, it should be understood that the present inventionshould not be interpreted as being limited to these embodiments, but isexplained according to the claims.

What is claimed is:
 1. A communication method, comprising: receiving, bya station from an access point, a beacon frame or a response frame,wherein the beacon frame or the response frame comprise a first value ofa timer; starting to decrease the timer from the first value, whereinthe decreasing the timer comprises: progressively decreasing the timerwith time when a channel for uplink transmission is idle and suspendingthe progressive decreasing of the timer when the channel is busy; whenthe station receives, from the access point, a trigger frame thatcarries information about an uplink transmission resource before thetimer reaches 0, wherein refraining from using a contention accessmanner that is based on carrier sense multiple access with collisionavoidance (CSMA/CA); sending, by the station to the access point, uplinktransmission data according to the trigger frame; and when receiving thetrigger frame, resetting, by the station, the timer based on a secondvalue that is specified by the access point, wherein the second value isspecified in a message frame, and the timer is reset by multiplying acurrent value of the timer by the second value; and when the station hasnot received a trigger frame from the access point before the timerreaches 0, accessing, by the station, a channel in a contention accessmanner that is based on CSMA/CA.
 2. The communication method accordingto claim 1, further comprising: receiving a radio frame sent by theaccess point, wherein the radio frame indicates sending time of thetrigger frame, and the radio frame is an association response frame, abeacon frame, or a response frame of the access point to a received dataframe.
 3. The communication method according to claim 1, wherein theinformation about the uplink transmission resource comprises at leastone of the following: a packet arrival interval, packet sizeinformation, or traffic rate information.
 4. A communication apparatus,comprising: a receiver; a transmitter; at least one processor; and oneor more memories coupled to the at least one processor and storingprogramming instructions for execution by the at least one processor tocause the apparatus to: receive, through the receiver, from an accesspoint, a beacon frame or a response frame, wherein the beacon frame orthe response frame comprises a first value of a timer; start to decreasethe timer from the first value, wherein the decreasing the timercomprises: progressively decreasing the timer with time when a channelfor uplink transmission is idle and suspending the progressivedecreasing of the timer when the channel is busy; if the apparatusreceives, from the access point, a trigger frame that carriesinformation about an uplink transmission resource before the timerreaches 0, refrain from using a contention access manner that is basedon carrier sense multiple access with collision avoidance (CSMA/CA);send, through the transmitter, to the access point, uplink transmissiondata according to the trigger frame; and when receiving the triggerframe, reset the timer based on a second value that is specified by theaccess point, wherein the second value is specified in a message frame,and the timer is reset by multiplying a current value of the timer bythe second value; and if the apparatus has not received, from the accesspoint, a trigger frame from the access point before the timer reaches 0,access a channel in a contention access manner that is based on CSMA/CA.5. The communication apparatus according to claim 4, wherein the one ormore memories store programming instructions for execution by the atleast one processor to cause the apparatus to: receive, through thereceiver a radio frame sent by the access point, wherein the radio frameindicates sending time of the trigger frame, and the radio frame is anassociation response frame, a beacon frame, or a response frame of theaccess point to a received data frame.
 6. The communication apparatusaccording to claim 4, wherein the information about the uplinktransmission resource comprises at least one of the following: a packetarrival interval, packet size information, or traffic rate information.7. One or more non-transitory computer-readable media storing computerinstructions, that when executed by one or more processors, cause acomputing device to perform operations comprising: receiving, by astation from an access point, a beacon frame or a response frame,wherein the beacon frame or the response frame comprise a first value ofa timer; starting to decrease the timer from the first value, whereinthe decreasing the timer comprises: progressively decreasing the timerwith time when a channel for uplink transmission is idle and suspendingthe progressive decreasing of the timer when the channel is busy; whenthe station receives, from the access point, a trigger frame thatcarries information about an uplink transmission resource before thetimer reaches 0, wherein refraining from using a contention accessmanner that is based on carrier sense multiple access with collisionavoidance (CSMA/CA); sending, by the station to the access point, uplinktransmission data according to the trigger frame; and when receiving thetrigger frame, resetting, by the station, the timer based on a secondvalue that is specified by the access point, wherein the second value isspecified in a message frame, and the timer is reset by multiplying acurrent value of the timer by the second value; and when the station hasnot received a trigger frame from the access point before the timerreaches 0, accessing, by the station, a channel in a contention accessmanner that is based on CSMA/CA.
 8. The one or more non-transitorycomputer-readable media according to claim 7, wherein the operationsfurther comprise: receiving a radio frame sent by the access point,wherein the radio frame indicates sending time of the trigger frame, andthe radio frame is an association response frame, a beacon frame, or aresponse frame of the access point to a received data frame.
 9. The oneor more non-transitory computer-readable media according to claim 7,wherein the information about the uplink transmission resource comprisesat least one of the following: a packet arrival interval, packet sizeinformation, or traffic rate information.